Neon tetra disease?

[tamtam]

Is anyone familiar with this? On Thursday night I picked up 5 new neons for my tank(only other tank mates are a school of rasboras), I woke up the next morning and 1 was dead and another was looking pretty miserable. He was off on his own near the surface, very skinny and sort of bent looking, looking like parts of his fins were torn off. He's still alive today and in the same shape. Hanging out near the heater and not doing anything but pretty much floating around an inch below surface.

I've been checking water prams a couple times a day and everything is ok. I just went to check the tank and 1 of my rasboras was dead and 2 of the other neons are looking questionable. They are still schooling but aren't looking like they were this morning. It's hard to explain how they look different.. Like the top of their "head" right before the fin is a little sunken looking.. The coloring isn't the same.. their whole body shape is a little bit off.

MY rasbora was totally fine this morning. No signs of being ill or anything and all of a sudden he was dead.

I'm pretty stressed out about this. I'm pretty worried I'm going to loose my whole tank. The neons are on warrenty still but if they are sick then I'm guessing the whole tank at the store is a no go too.